It is generally known in the art of internal combustion engine design to use charge motion control valves in an intake manifold. The “charge” is understood to mean the air or air-fuel mixture being delivered to the combustion camber. “Charge motion” is a purposely induced, preferential movement of the charge for more controlled burning in the combustion chamber. There are basically two main types of induced charge motion: tumble and swirl. “Tumble” is understood to mean bulk charge rotation about an axis perpendicular to the longitudinal axis of the cylinder. “Swirl” is bulk charge rotation about an axis generally parallel to the cylinder axis. Today's prevalent method for varying tumble and/or swirl in an engine is through the use of valves that are configured to preferentially direct air flow through the intake runners and/or combustion chamber. The valves may be programmed to work during certain selected engine conditions to control mixing in the combustion chamber.
FIG. 1 is a prior art representation of an engine cylinder 1 having a piston 2, an air intake valve 3 and air exhaust valve 4 connected at the cylinder head 5. A prior art tumble control valve is typically positioned in the air intake runner 6 which extends from the air intake manifold (not shown in FIG. 1), leading to cylinder 1. A prior art tumble control valve generally comprises a valve flap or blade 7 pivotally disposed within the intake runner 6. The valve blade 7 pivots about point 7′ between fully open (dotted line) and fully closed (solid line) positions. When in the fully closed position shown in solid line, blade 7 lies substantially perpendicular to the longitudinal extent of intake runner 6. In this position, the bottom (longer) edge of the blade 7 lies in close relationship to the internal cavity of the runner 6, thus effectively sealing off this area to air flow. Conversely, the top (shorter) edge of the blade 7 lies in spaced relation to the internal cavity of the runner 6 to define a gap wherethrough air may flow. Thus, in the fully closed position of the valve blade 7, maximum tumble is generated in engine cylinder 7 since the air flow represented by the directional arrows is forced to pass through the gap defined close to the internal cavity wall of the runner.
When engine conditions indicate tumble or swirl are not needed, the valve 7 opens (dotted line) to allow air flow through the runner in the normal manner. However, it will be appreciated that even when the valve blade is in the fully open position (extending parallel to the extent of the runner 6), the mass of the blade remains positioned within the runner 6 and therefore necessarily blocks some of the air flow through the runner. Even a slight a blockage in the air intake runner is undesirable in that it diminishes engine performance.
It would therefore be desirable to have a charge motion control valve and method which does not present any blockage to air flow through the runner when the valve is in the fully opened position.
The charge motion control valves are typically positioned in each air intake runner in close proximity to the inlet to the engine head port and intake valve. If the valves are located at too great a distance, the tumble or swirl effect is reduced or eliminated before the air intake charge enters the combustion chamber. In some applications, a shelf or flow divider is placed in the runner, just downstream of the charge motion valve, to extend the biased flow closer to the intake valve in the head. Because of the need to have the charge motion control valves close to the intake valve in the head, V6 and V8 applications of tumble and swirl control have required two sets of valves, one set for the right bank and one set for the left bank of the engine.
A common actuator is usually employed to drive both sets of motion control valves. An exposed linkage extends from either side of the actuator to drive each of the two sets of valves. This linkage arrangement between the two sets of valves has drawbacks such as wear and breakage of the linkage parts, the added parts cost and space requirements within the engine compartment, for example. Although two shafts and associated linkages to the actuator are not required In a straight, in-line engine, the fact that the tumble control valves must be placed close to the cylinder heads places limitations on engine and manifold design and creates possible valve failure due to the high heat environment in the vicinity of the combustion chambers.
It would therefore be furthermore desirable to have a charge motion control valve and method for a V-type engine that does not require external linkages nor individual charge motion control valves for each set of engine cylinder banks.